Detergent-containing lubricating oil



United States atent )fiiice 3,050,464 DETERGENT-CONTAINING LUBRICATING 011. Thomas F. Brown, Barnston, and Peter Mathews, Hartford, England, assignors to Universal Oil Products Company, Des Plaines, 111., a corporation of Delaware No Drawing. Filed Apr. 1, 1959, Ser. No. 803,366 6 Claims. (Cl. 252-33) This invention relates to a process for the production of oil-soluble petroleum sulfonates derived from a lubricating oil stock and to a lubricating oil composition con taining said sulfonates. More specifically, this invention concerns a process for producing more desirable oilsoluble petroleum sulfonates, for increasing the yield of oil-soluble sulfonates from a given lubricating oil boiling range petroleum stock and to an improved lubricating oil composition comprising a petroleum fraction having lubricating oil qualities and containing substantially neutral sulfonates derived from the petroleum stock itself.

It is well known that lubricating oil stocks contain varying amounts of aromatic components which are capable of being sulfonated to produce sulfonic acids. These acids may be neutralized, recovered from the sulfonated oil as sulfonates and added to lubricating oil in small quantities to form a lubricant composition having, in addition to the desired lubricating qualities of the oil, the surface active properties of the petroleum sulfonate contained in the composition. The oil containing the dissolved sulfonate provide a highly desirable lubricating oil composition which continuously maintains in suspen sion the harmful resins, carbon particles and dirt generally present in and accumulating in the crankcase of an internal combustion engine. Although it is known that when such lubricating oil stocks are sulfonated, the aromatic components of the oil are thereby converted to their sulfonate derivatives, the resulting composition, although improved with respect to its lubricating qualities by virtue of the presence of such detersive sulfonates therein, nevertheless contains an appreciable proportion of naphthenic hydrocarbons which reduce the viscosity index of the oil. Accordingly, it becomes desirable to not only eliminate as much of the naphthene content of the lubricating oil as possible by conversion to other, less detrimental hydrocarbons, but to convert, if possible these naphthenes to aromatics which increase the proportion of sulfonatable components in the oil which may be converted to desirable sulfonates having surface activity in the lubricating oil composition. The present process has as its primary objective the treatment of a petroleum lubricating oil charge stock in a reforming reaction prior to the sulfonation stage of the process whereby the naphthenes present in the lubricating oil stock are converted to aromatic hydrocarbons of the monocyclic alkylaryl type, sulfonatable to desirable lubricating oil detergents. The present process thu not only has the desirable effect of reducing the naphthene content of the residual oil stock, which increases its viscosity index by removing the components therefrom which reduce the viscosity index, but the process simultaneously increases the conversion of the hydrocarbon components of the lubricating oil stock to aromatic hydrocarbons, which may be sulfonated in the succeeding stages of the process to form an enhanced yield of desirable surface active sulfonates. The sulfonates which are the source of the surface active components in the ultimate lubricating oil product are thus formed in situ from hydrocarbon components present in the starting material.

In one of its embodiments this invention relates to a process for the production of a lubricating oil composition which comprises contacting a naphthene-containing 2 lubricating oil fraction boiling from about 300 to about 500 C. with a reforming catalyst containing a noble metal selected from the elements of group VIII of the periodic table at reforming conditions, subjecting the resulting hydrocarbon product containing aromatic hy= drocarbons to sulfonation at sulfonatin'g conditions sufli= cient to convert a substantial proportion of the aromatic hydrocarbon components to their sulfonated derivatives and thereafter neutralizing the sulfonated oil to form a lubricating oil containing dissolved aromatic sulfonate.

A more specific embodiment of the present invention relates to a process for producing a lubricating oil composition containing a surface active sulfonate formed in situ from a component of said oil which comprises contacting a petroleum lubricating oil stock containing a naphthene hydrocarbon at a temperature of from about 300 to about 450 C. with a reforming catalyst containing from 0.01 to about 3% by weight of platinum, and 0.01 to about 3% by weight of combined halogen supported on alumina, recovering a reformed hydrocarbon product of increased aromatic content, subjecting said reformed product to sulfonation at sulfonation reaction conditions suflicient to convert the aromatic hydrocarbon components of said product to their sulfonic acid derivatives and adding a basic reagent to the sulfonation mixture in suificient quantity to form a substantially neutral lubricating oil sulfonate concentrate and mixing said 0oncentrate with a parafiin-base lubricating oil stock to form a lubricating oil composition containing from about 0.5 to about 3% by weight of said sulfonate.

Suitable initial starting materials utilizable as feed stocks in the present process are lubricating oil fractions of petroleum or certain petroleum conversion products, generally and preferably, having a boiling range of from about 300 to about 500 C. and a viscosity range of from about to about 900 units on the Saybolt Universal seconds scale at F (or from about 15 to about 200 centistokes). Hydrocarbon fractions having the foregoing properties are substantially naphthenic in charactor and may contain from 5% to over 50% naphthene hydrocarbons, depending upon the source of the crude oil from which the lubricating oil fraction is separated. Thus, the fraction may be and is preferably derived from a virgin stock, such as, a crude oil of Mid-Continent, Pennsylvania, Peruvian, or other origin, an appropriately boiling fraction of a catalytically or thermally cracked stock, or other source containing naphthenic hydrocar bons and having the indicated properties. The naphthenic components present in these fractions are generally monoand polycyclic in character and contain one or more alkyl ring substituents, which upon dehydrogenation in the presence of the group VIII metal-containin g catalyst of this invention produce primarily monocyclic aromatic hydrocarbons capable of being readily sulfonated to form alkylaryl sulfonates having a high degree of surface activity in the ultimate lubricating oil product. The lubricating oil fraction utilized as starting material, if it contains an appreciable proportion of olefins, mercaptans and nitrogenous compounds, is preferably subjected to a hydrogenation pretreatment in order to saturate the olefinic hydrocarbons and to reduce any sulfurand/or nitrogen-containing compounds present in the initial feed stock. These contaminants, if permitted to remain in the charge stock, tend to deactivate the catalyst provided for the reforming stage of the process and, accordingly are desirably removed from the feed stock prior to such catalytic dehydrogenation. The prehydrogenation of such stocks is readily eifected by contacting the same with a suitable hydrogenation catalyst, such as nickel, nickel oxide or nickel sulfide supported on an inert refractory metal oxide, such as alumina, a nickel-molybdena composite supported on a refractory metal oxide,

or other catalyst well-known in the art for effecting hydrogenation at relatively mild conditions, such as pressures of from atmospheric to atmospheres, and temperatures of from about 100 to about 300 C.

In order to remove resinous and colored impurities from the lubricating oil feed stock, the latter may be contacted at an elevated temperature with a refractory clay or with an activated adsorbent which removes such resinous and colored components by adsorption. Thus, for example, the lube oil stock may be passed through a bed of montmorillonite clay, Attapulgus clay, diatomaceous earth, fullers earth, charcoal or other adsorbent at temperatures of from about 100 to about 350C, collecting the treated stock as an effluent from the clay bed.

The raw oil stock generally contains aromatic hydrocarbons which usually also yield desirable surface active sulfonates for use in compounding the present lubricating oil composition. Although these aromatics produce desirable sulfonates, they are preferably removed from the lubricating oil feed stock prior to the reforming stage of the instant process, for example, by solvent extraction, acid treatment, adsorption or by other means which effect their removal, because their presence in the reforming reaction zone reduces the net conversion of naphthenes to aromatic components during the reforming stage. Thus, the lube oil stock may be passed (preferably in diluted form) over or through a bed of silica gel adsorbent to remove the aromatic components, which may thereafter be recovered from the absorbent and, if desired, separately sulfonated and the sulfonates incorporated into the present lubricating oil composition, or discarded, if preferred. Suitable diluents for this purpose are such materials as n-butane, n-pentane, n-hexane, etc., which are not adsorbed by the silica gel and which may be readily distilled from the oil stock after such pretreatment. The oil stock may also be pre-sulfonated with concentrated sulfuric acid, for example, or with an oleum pretreatment to convert the aromatics initially present in the stock to their sulfonic acids which may be thereafter completely removed by extracting the acid-treated stock with an organic solvent and the recovered sulfonic acids either discarded (if not desired in the ultimate composition) or recovered and added thereto. Other methods of pretreatment such as solvent extraction (e.g. with liquid sulfur dioxide) may be utilized to recover the aromatics initially present in the feed stock, in accordance with Well-known procedures for this purpose.

The preferred lubricating oil stocks, utilizable as starting materials in the present process, are the straight run lubricating oil fractions from which the wax paratfins have been separated by crystallization, e.g.; by cooling the lube oil fraction to a temperature of from about 50 to about 10 C. and thereafter filtering the cooled oil to remove wax crystals therefrom, the crystallized wax comprising high molecular weight, straight chain paraffin hydrocarbons. The lube oil stock may be diluted, prior to such cooling, with a low viscosity normal or cycloparafiin, such as propane, n-butane, n-pentane, n-heptane, nhexane, cyclohexane, etc. in order to reduce the viscosity of the oil and permit the normally highly viscous, chilled oil to flow through the filters at a greater rate.

In accordance with the process of the present invention, the lubricating oil charge stock, preferably pretreated to remove wax components and resinous or highly colored impurities, as well as aromatic, nitrogen and sulfur compounds normally present in the untreated lubricating oil fraction separated from crude oil, is thereafter subjected to a reforming conversion whereby the naphthenic components present in the lubricating oil charge stock are dehydrogenated and converted to aromatic hydrocarbons, sulfonatable in the succeeding stages of the present process to form desirable surface active sulfonate components. The latter treatment is effected in the presence of a dehydrogenation catalyst of the platinum, palladium or iridium-containing type (i.e., a supported group VIII noble metal), especially suitable in the present process for aromatization of the naphthenic components of the lubricating oil charge stock in a once-through process flow. These catalysts (preferably, a platinum-containing refractory metal oxide composite) are to be distinguished from other hydrogenation-dehydrogenation catalysts for aromatization of naphthenic lube oils on the basis of the outstanding advantages accompanying their use in the present process, including their ability to effect a high degree of naphthene-to-aromatic conversion on a oncethrough basis, with substantially non-existent decomposition (carbonization) of the charge stock. The present aromatization catalysts (especially platinum-containing composites) remove hydrogen from the naphthenes present in the lube oil at a high order of efiiciency, converting the same to aromatic hydrocarbons, substantially to the extinction of naphthenes, at a relatively low temperature level, at atmospheric or slightly superatmospheric pressures and with little or not decomposition (e.g., carbon ization or cracking) of the hydrocarbon components present in the lube oil stock. In comparison with such catalysts as supported nickel, nickel sulfide, or nickel oxide composites, nickel and/ or cobalt polymolybdates or thiomolybdates supported on alumina, chromia-alumina composites, vanadium oxide and/or molybdenum oxide supported by alumina or silica and a wide variety of other dehydrogenation-reforming catalysts, the latter catalysts require substantially higher temperatures and pressures to obtain conversions even remotely approaching the yields realized with the present platinum-containing catalysts and the use of such other catalysts is generally accompanied by substantial hydrocracking of the lubricating oil feed components and carbon deposition on the catalyst. A further marked advantage of the present platinum-containing dehydrogenation catalysts over the aforementioned other catalyst composites is the fact that substantially complete conversion of the naphthenic components to aromatic hydrocarbons may be realized in a once-through operation, thereby eliminating the necessity of recycling unconverted naphthenes or permitting them to remain in the lube oil product to the detriment of the resulting product and to a lower yield of ultimately desired detergent. The latter alternatives are generally found to be necessary when utilizing the aforementioned catalysts of the prior art.

The present, preferred platinum-containing dehydrogenation catalysts are composites of platinum with a refractory metal oxide support, such as alumina, silica, mixtures or composites of alumina and silica, magnesia or carbon (such as charcoal or graphite), and preferably contain, besides platinum, an acidic component likewise supported on the refractory inert support. One of the preferred catalysts for use in the present process for effecting dehydrogenation of naphthenes to form aromatics therefrom is a mixture of platinum and an acidic component supported on alumina, the catalyst being described in US Patent 2,478,916, issued August 16, 1949. A particularly preferred catalyst composition useful in the dehydrogenation stage of the process comprises alumina composited with platinum and a combined halogen, of the type described in US. Patent 2,479,109, issued August 16, 1949. The preferred platinum-alumina-combined halogen type of catalyst contains from about 0.01% to about 1% by weight of a group VIII noble metal, such as platinum, palladium, rhodium and/ or iridium (preferably, platinum) and from about 0.1% to about 5% by weight of a combined halogen, such as chlorine, or a mixture of combined halogens, such as chlorine and fluorine in an amount of from about 0.1% to about 3% by weight of the total composite. The acidic component of the catalyst, which in the above preferred platinum-combined halogen-alumina composites is a halogen combined with the alumina, may also be supplied by other acidic or acidacting components, such as silica composited with the alumina in the form of an aluminum silicate, aluminum chloride, aluminum oxychloride, or a free acid itself, such as hydrochloric, hydrofluoric, sulfuric or phosphoric acid, etc.

Preference is herein given the platinum or other group VIII noble metal-alumina composites, over nickel and/0r cobalt-alumina composites and other dehydrogenation catalysts of the prior art, on the further grounds that the preferred catalysts may be utilized for longer periods of time without the necessity for reactivation, being capable of processing greater quantities of charge stock before becoming deactivated by the accumulation or deposition of resinous and/or carbonaceous deposits on the catalyst particle. These catalysts are also distinguished over the aforementioned nickel and/or cobalt catalysts of the prior art by their ability to effect the desired dehydrogenation of the lube oil naphthenes in the absence of extraneous sources of hydrogen; that is, the dehydrogenation and aromatization of the lube oil feed stock occurs in the presence of hydrogen formed in situ by dehydrogenation of the lube oil naphthenes. It is to be emphasized, however, that such acidic components are not necessarily required or even desired in the make-up of the catalyst composition, the platinum or other group VIII noble metal, supported by the refractory support, being the essential, irreducible minimum components of the catalyst.

Catalytic dehydrogenation and aromatization of the naphthenic lubricating oil feed stock, constituting the first stage of the present process, after separation of the desired fraction for treatment herein, is effected by contacting the oil stock with a group VIII noble metal-containing reforming catalyst of the aforementioned type and composition at a temperature of from about 250 to about 450 C., and more preferably, within the range of from about 300 to about 400 C., and at a pressure within the range .of from atmospheric to about 1000 pounds per square inch and more preferably, at substantially atmospheric pressure. Although effective aromatization may be obtained in the absence of an extraneous source of hydrogen (hydrogen being produced in a state of high purity as a result of dehydrogenation of the naphthenes present in the lube oil stock), it is generally preferred to provide an extraneous supply of hydrogen to the catalytic reaction zone in order to minimize carbonization and decomposition of the feed stock. When thus supplied with an outside source of hydrogen, the quantity of hydrogen supplied to the reaction zone may be as high as to 1 moles of hydrogen per mole of hydrocarbon. The residence time of the feed stock with the catalyst may range from an average of one-half to about six hours or more, depending upon the temperature, pressure and other factors involved in the aromatization reaction.

The conversion is readily effected by passing the feed stock at the above temperature and pressure conditions (sufiicient in any event to maintain the feed stock in substantially liquid phase) over a fixed bed of the present aromatization catalyst or the latter may be supplied. at aromatizing conditions to the reaction zone in the form of relatively finely divided particles suspended in the liquid feed stock, being thereafter settled or filtered from the resulting aromatized product.

The reforming stage of the present process is operated at conversion conditions of temperature, pressure and. residence time of the charge stock with the catalyst sufficient to effect substantially complete dehydrogenation of the naphthenes present in the oil stock, but preferably limited in the depth of conversion only to such dehydrogenation of the naphthene components. At more severe reforming conditions and when the contact between charge stock and catalyst is prolonged to more extended periods, the catalyst effects incidental side reactions, including isomerization of the cyclic components to polycyclic aromatics which upon sulfonation yield di and polysulfonic acid derivatives. The sulfonates of the latter acids are of the water-soluble type and are generally less effective and consequently less desirable surface active agents for use in lubricating oil compositions. In addition to such isomerization at relatively more severe reforming conditions, the hydrocarbon components tend to cyclicize to aromatics having no allryl side chains which, also, are not desirable subjects for sulfonation in that they yield oil-immiscible, low order surface activity sulfonates. For the foregoing reasons, the reforming stage of the present process is preferably limited in its severity to conditions which effect dehydrogenation only of the naphthenes present in the lube oil stock, as measured by the yield of hydrogen released via dehydrogenation of the naphthenes present in the stock. The desirable limits of such dehydrogenation are dependent upon the naphthene content of the charge stock. which is generally within the range of from about 10 to about percent by Weight of the lube oil stock. Assuming the production of three moles of hydrogen per mole of naphthene undergoing aromatization, the most desirable sulfonates are formed by dehydrogenating the lube oil stock to yield from about 0.3 to about 2.5, and more preferably, from about 0.8 to about 1.8 cubic feet of hydrogen at normal temperature (0 C.) and pressure (atmospheric) per pound of lube oil stock charged to the aromatization stage of the process.

The aromatization reaction product, after the desired period of contact with the catalyst herein provided, is

passed through a heat exchanger and cooled sufficiently to prepare the resulting aromatized oil for the subsequent sulfonation stage of the process. If desired, or if required, the lubricating oil may receive an intermediate treatment with clay or other activated adsorbent to remove colored impurities, resins or carbonaceous particles, if any, in suspension in the aromatized oil.

The lubricating oil product of the aromatization reaction containing a substantial proportion of monocyclic aromatic hydrocmbons and alkyl aromatic hydrocarbons is subjected to sulfonation by contacting the product of the aromatization stage in liquid phase with a suitable sulfonating agent at sulfonation reaction conditions sufficient to convert the aromatic and allryl aromatic hydrocarbon components of the first stage treatment present in the aromatized oil to their monosulfonic acid derivatives. Suitable sulfonating agents for this purpose include a number of typical reagents recognized for this purpose, such as relatively concentrated sulfuric acid containing at least 95% by weight of the acid, oleum (comprising 100% sulfuric acid containing dissolved free sulfur trioxide in concentrations ranging up to about by weight of free sulfur trioxide), liquid, preferably stabilized sulfur trioxide itself, chlorosulfuric acid, fluorosulfonic acid and others widely recognized in the sulfonation art. The reaction conditions required for effecting rnonosulfonation of the aromatic components of the lubricating oil differ for the various sulfonating agents heretofore specified for this purpose. Thus, concentrated sulfuric acid requires temperatures of from about 5 to about 60 C., ratios of sulfuric acid to charge stock of from about 2 to l to about 8 to 1 moles of sulfuric acid per mole of aromatic hydrocarbon in the lubricating oil stock and sulfonation reaction periods (residence time) of from about 10 minutes to about 2 hours. When utilizing one of the more highly active sulfonating agents, such as oleum or liquid sulfur trioxide, suitable temperatures for effecting the sulfonation reaction may be Within the range of from about 30 to about +60 C. (more preferably, about 0 to about 20 C), utilizing molar ratios of free sulfur trioxide in the oleum or liquid to aromatic component in the lube oil feed stock of from about 1 to 1 to about 1.4 to 1 for S0 up to about 2.0 to 1 for oleum. Generally, the reaction is substantially instantaneous, but may be prolonged for periods up to about 2 hours or more in order to ensure complete monosulfonation of the aromatic components in the lube oil. In the use of the latter highly active sulfonating agents, the reaction mixture is preferably vigorously stirred during the addition of the sulfonating agent and/ or the feed stock; alternatively, the sulfonating agent may be mixed with an inert, volatile solvent, such as liquid sulfur dioxide, liquid propane, n-butane, Freon, or other volatile liquid which boils at the desired sulfonation temperature and thus evaporates at its boiling point when the heat of reaction causes the reaction mixture to exceed the desired sulfonation temperature. The process is usually conducted on a batch scale, although continuous methods may be adapted to the requirements of the process.

Following completion of the sulfonation reaction, as determined by the extent of convension of the aromatic components to their sulfonic acid derivatives, the reaction mixture is desirably allowed to settle in order to enable the excess sulfonating agent to be decanted from the upper hydrocarbon phase, the acid phase generally settling as a lower layer at the bottom of the reaction zone, particularly if a small amount of water, sufficient to convert the unreacted sulfuric acid to its monohydrate, is added to the sulfonation reaction mixture. Since the sulfonated aromatic hydrocarbons present in the lubricating oil stock are generally oil-soluble, the sulfonated mixture may be mixed with water to extract the excess sulfonating agent from the sulfonated lubricating oil and the aqueous phase containing the excess sulfonating agent withdrawn from the upper hydrocarbon-sulfonic acid phase.

After completion of the sulfonation reaction, the sulfonic acids present in the lubricating oil (as well as the sulfonic acids formed by sulfonating the initial feed stock, if desired) are neutralized with a suitable alkaline base, the sulfonate salt of which provides the desired sulfonate detergent in the lube oil product. Suitable neutralizing agents which convert the sulfonic acids present in the lube oil product to the desired surface active sulfonates may be selected from the oxides, hydroxides, and carbonates of (l) the alkali metals, such as sodium, lithium, potassium, etc. (preferably lithium hydroxide), (2) of the alkaline earth metals, such as calcium, magnesium, barium, and cesium (preferably barium hydroxide) or (3) from the hydroxide or a weak acid salt of aluminum which reacts with the sulfonic acids to form the aluminum sulfonate salt by double decomposition, the resulting neutral aromatic sulfonate salt thereafter being retained in solution within the lubricating oil stock. The neutralizing agent may be supplied in the form of an aqueous solution at any convenient concentration and more preferably in concentrated form, the substantially neutral lubricating oil containing the dissolved detersive sulfonates being thereafter withdrawn from the excess of the neutralizing reagent, separating as a lower aqueous phase.

Depending upon the source of the initial lubricating oil stock, the sulfonated product of the aromatization stage of the present process may contain from generally not less than by weight, up to about 40 or 50% by weight of the surface active sulfonic acid, after completion of the sulfonation reaction. The sulfonated product thereby constitutes a lubricating oil concentrate of the desired sulfonic acid which may thereafter be mixed with a lubricating oil stock, preferably a paraflinbase stock, to form. the ultimate lubricating oil composition suitable for use in internal combustion engines and containing from 0.5% to generally not more than about 3% by weight of the aromatic sulfonic acid or sulfonate salt. Thus, the primary product of the present combined aromatization-sulfonation process is a lubricating oil detergent concentrate which may be mixed with additional lubricating oil stock of the desired viscosity index, boiling point and other characteristics making it suitable for use as a lubricating oil stock, to provide the ultimate lubricating oil composition.

The present invention is further illustrated with respect to several of its specific embodiments in the following illustrative examples, which, however, are not intended to limit the generally broad scope of the present invention necessarily in accordance therewith.

EXAMPLE I A wax-free light engine distillate having a viscosity of about 37 centistokes at 60 C. and separated at bottoms from a Lobitos crude was subjected to solvent extraction with liquid sulfur dioxide, the extraction removing about 15% by weight of extract comprising aromatic hydrocarbons. The raffinate of the foregoing solvent extraction was then treated in two stages with 20% oleum (10 grams of oleum per 100 grams of oil) at 10 C. to remove aromatics initially present in the lubricating oil stock. The oil was thereafter neutralized with a concentrated aqueous sodium hydroxide solution and the aqueous phase separated from the hydrocarbon rafi'inate. The sodium. sulfonates dissolved in the neutral oil were extracted with 50 volume percent portions of ethanol in 4 extraction stages and the recovered oil thereafter mixed with 10% of its weight of fullers earth at 80 C. for 1 hour, followed by filtering the suspended solid from the oil. The sulfonates thus extracted from the oil were reserved for incorporation into the final lubricating oil composition. The recovered oil filtrate which was utilized as the feed stock in the subsequent aromatization reactions has the following physical properties, shown in Table I, below:

Table I Refractive index, 11 1.4825 Specific gravity, 60/ 60 F 0.893 Viscosity at F, cs 78.9 Viscosity at F., cs 26.7 Viscosity at 210 F., cs 7.7 Water, percent 0.01 Nitrogen, percent 0.02

Sulfur, percent 0.0005 Lead, parts per billion 20 Saybolt color +23 225 grams of the oil prepared as indicated and described above was mixed at 330 C. with 22.5 grams of Platforming catalyst comprising one-eighth inch spheres of a composite of platinum supported on an alumina base and containing combined halogen, the catalyst containing 0.375% by weight of platinum, 0.35% by weight of combined chlorine and 0.35 by weight of combined fluorine. After 74 minutes of contact at atmospheric pressure, the oil had yielded 16.8 liters of hydrogen (99.5% pure) and after cooling, the processed oil was found to contain 26% by weight of aromatic hydrocarbons measured by chromatographic analysis utilizing silica gel as adsorbent. 40 grams of the dehydrogenated oil was cooled to 20 C. in a Dry Ice bath and rapidly stirred as 15.6 grams of 20% oleum in three volumes of liquid sulfur dioxide was added to the oil over a period of about one-half hour. Thereafter, about 8 cc. of distilled water was added to the sulfonation mixture, excess sulfur dioxide was removed by volatilization and 17 grams of aqueous acid was decanted from the upper oil layer. Analysis of the decanted aqueous phase indicated that substantially none of the sulfonic acids Were extracted as an aqueous extract by treatment of the sulfonation mixture with water. The acid oil remaining was then neutralized by adding 200 cc. of 50 volume percent isopropanol and 15 cc. of a 20% aqueous solution of sodium hydroxide. A lowermost layer consisting of 5 cc. of aqueous sodium sulfate solution was removed by draining from the resulting mixture. The aqueous alcohol layer was then separated from the oil and evaporated to dryness, yielding 13.6 grams of pure sodium alkylaryl sulfonates, equal to a yield of 34% on the original feed stock. The sulfonates were completely soluble in oil, having a molecular weight of about 430.

Another sample of the dehydrogenated oil, sulfonated in accordance with the above procedure, was neutralized directly with an aqueous solution of lithium hydroxide and the excess of caustic withdrawn from the resulting oil layer which separated on settling. The aqueous phase contained substantially none of the sulfonate and the upper, oil layer contained the lithium sulfonates in solution. One volume of the oil layer mixed with 20 volumes of a parafiinic base oil from which naphthenes have been removed produced a detergent oil composition containing approximately 1.5% by weight of lithium sulfonates. The resulting oil composition was a highly effective lubricating oil which maintained in suspension in the oil any carbonaceous and resinous deposits formed during the use of the oil in an automotive engine crankcase in a test run for 136 hours, during 96 hours of which the engine was in operation for ten minutes out of each hour and hours of which the engine was in continuous operation.

The lithium sulfonates recovered from the aromatized oil via sulfonation and neutralization were mixed with the lithium hydroxide neutralized sulfonic acids produced in the initial pretreatment of the raw oil stock prior to dehydrogenation thereof. These sulfonates were also oilsoluble and in admixture with the sulfonates formed from the dehydrogenated naphthenes, produced a highly effective lubricating oil composition when the concentration of mixed sulfonates in the lube oil stock was from 0.5 to 3.5% by weight.

EXAMPLE II 2000 grams of the acid-pretreated oil specified in Example I, above, was heated to 330 C. with 200 grams of inch pellets of a platinum-containing catalyst comprising an alumina-supported composite of 0.5% by weight of platinum, 0.35% by weight of combined chlorine and 0.35 by weight of combined fluorine. The oil-catalyst mixture was heated to a temperature of about 325 C. for approximately 4 hours, yielding 192 liters (at standard temperature and pressure) of 99.5% hydro gen. The aromatized oil contains 37.5% by weight of aromatic hydrocarbons, thus indicating substantially more extensive dehydrogenation of the feed stock.

25 grams of dehydrogenated oil was treated with 18.8 grams of 20% oleum in a solution of liquid sulfur dioxide, the oleum being added over a period of approximately /2 hour to the oil maintained at about -20 C. After vaporization of the sulfur dioxide, the mixture was neutralized with a 20% aqueous sodium hydroxide solution and thereafter mixed with 100 volume percent of water, an oil layer separating from the resulting aqueous phase. The sulfonates formed by neutralization of the sulfonated oil remained partially in solution in the oil and were partially extracted in the aqueous phase. The resulting detergent concentrate in solution in the oil, when mixed with additional lubricating oil stock, produced a detergent lubricating oil composition, which, however, under engine test conditions, was not as eifective as the sulfonates formed under the less extensive dehydrogenation reaction conditions of Example I, above. Extraction of the sulfonates with isopropanol from the sulfonated oil yielded sulfonates having a molecular weight of about 414.

EXAMPLE III In a series of runs the aromatizing activity of nickelcontaining dehydrogenation catalysts and other wellknown dehydrogenation catalysts of the prior art were compared with the platinum-containing catalysts of the present invention for the conversion of the naphthenes present in the lubricating oil stock, described and specitied in Example I above and the results of such compari son are herewith presented below. In the runs utilizing nickel and other known dehydrogenation catalysts, the temperatures, pressures and other operating conditions were adjusted to relatively more severe levels in order to obtain a reasonable degree of aromatization, approaching 10 the depth of aromatization utilizing the above platinumcontaining catalysts. In a series of 12 separate runs, each utilizing 10 grams of Raney nickel catalyst per grams of oil, wherein the time of contact between the lubricating oil charge stock and catalyst was varied from 87 minutes to 337 minutes and the reaction temperature was varied from 210 C. to 371 C., the resulting product sulfonated and neutralized in accordance with the procedure described in Example I above, at substantially identical reaction conditions and with the same ratio of sulfonating agent to aromatized lubricating oil stock, the yield of aromatic hydrocarbon components in the aromatized oil varied from 4 to about 8%, the aromatic sulfonate components present in the sulfonated oil were of higher molecular weight (averaging about 460) and the sulfonates were of poorer quality, being generally more soluble in water and less soluble in the hydrocarbon phase. The gas evolved from the lubricating oil stock as a result of treatment with the Raney nickel catalyst contained from 21.6 to about 62.4% hydrogen for the 12 runs, from 77% to 15.8% by weight of methane, and varying amounts of higher molecular weight light, non-condensable gases, indicating substantially greater cracking and dealkylation of the naphthenes and aromatics present in the lubricating oil stock, compared to the foregoing runs utilizing a platinum-containing catalyst in which straightforward dehydrogenation predominantly characterized the reaction and the gaseous effluent consisted of hydrogen of 99l% purity.

In a similar series of runs utilizing cobalt thiomolybdate-alumina and nickel oxide-alumina composite catalysts, the results with respect to yield and quality of desired detergent sulfonate and the presence of light hydrocarbons in the gases evolved from the dehydrogenation reaction were generally similar to the results obtained for Raney nickel catalysts, indicating that such catalysts were also much less effective for the aromatization of the naphthenic base lubricating oil stock than the aforementioned platinum-containing catalysts.

We claim as our invention:

1. A process for the production of a lubricating oil composition containing an oil-soluble detergent component which comprises contacting a naphthene-containing petroleum lubricating oil boiling from about 300 to about 500 C. with a hydrocarbon reforming catalyst containing a noble metal of group VIII of the periodic table at aromatizing conditions whereby the naphthene components in said oil are converted to aromatic hydrocarbons, subjecting the resulting reformed oil to sulfonation at sulfonating reaction conditions sufficient to convert a substantial proportion of the aromatic components to their sulfonated derivatives and thereafter neutralizing the sulfonated oil with an alkaline base.

2. The process of claim 1 further characterized in that said catalyst contains an acidic component.

3. The process of claim 1 further characterized in that said reforming catalyst is a composite of platinum and a combined halogen supported by alumina.

4. The process of claim 1 further characterized in that said oil is dehydrogenated at dehydrogenation reaction conditions suflicient to release from 0.3 to about 2.5 cubic feet of hydrogen at standard conditions per pound of oil from the oil.

5. The process of claim 2 further characterized in that said acidic component is a halogen combined with a refractory metal oxide support.

6. In the production of a lubricating composition containing an oil-soluble sulfonate detergent component, wherein a naphthene-containing petroleum lubricating oil stock boiling between about 300 C. and 500 C. is sulfonated and the sulfonated oil neutralized, the method of increasing the content of oil-soluble petroleum sulfonates in said composition which comprises contacting said naphthene-containing petroleum stock, prior to the sulfo- 1 1 nation thereof, With a hydrocarbon reforming catalyst containing a noble metal of group VIII of the periodic table at aromatizing conditions to convert naphthenes to aromatic hydrocarbons Which are sulfonated during the subsequent sulfonation of the petroleum stock.

References Cited in the file of this patent UNITED STATES PATENTS Flett Nov. 13, 1945 12 Haensel Aug. 16, 1949 Brandon July 10, 1951 Asseff et al Nov. 4, 1952 Dinwiddle et a1 Mar. 24, 1953 McDonald et al Sept. 24, 1957 Warren et al June 17, 1958 Walker Dec. 23, 1968 Honeycutt Mar. 3 1, 1959 Gleim Sept. 22, 1959 Faust Dec. 8, 1959 Thompson et a1. Apr. 5, 1960 

1. A PROCESS FOR THE PRODUCTION OF A LUBRICATING OIL COMPOSITION CONTAINING AN OIL-SOLUBLE DETERGENT COMPONENT WHICH COMPRISES CONTACTING A NAPHTHENE-CONTAINING PETROLEUM LUBRICATING OIL BOILING FROM ABOUT 300* TO ABOUT 500* C, WITH A HYDROCARBON REFORMING CATALYST CONTAINING A NOBLE METAL OF GROUP VIII OF THE PERIODIC TABLE AT AROMATIZING CONDITIONS WHEREBY THE NAPHTHENE COMPONENTS IN SAID OIL ARE CONVERTED TO AROMATIC HYDROCARBONS, SUBJECTING THE RESULTING REFORMED OIL TO SULFONATION AT SULFONATING REACTION CONDITIONS SUFFICIENT TO CONVERT A SUBSTANTIAL DERIVATIVES AND THEREAFTER NEUTRALIZING THE SULFONATED OIL WITH AN ALKALINE BASE. 